Arun Kumar Das

Detection and quantification of some plant growth regulators in a seaweed-based foliar spray employing a mass spectrometric technique sans chromatographic separation.

The sap expelled from the fresh harvest of Kappaphycus alvarezii , a red seaweed growing in tropical waters, has been reported to be a potent foliar spray. Tandem mass spectrometry of various organic extracts of the sap confirmed the presence of the plant growth regulators (PGRs) indole 3-acetic acid, gibberellin GA(3), kinetin, and zeatin. These PGRs were quantified in fresh state and after 1 year of storage by ESI-MS without recourse to chromatographic separation. Quantification was validated against HPLC data. The results may be useful in correlating with the efficacy of the sap. The methodology was extended to two other seaweeds. The method developed is convenient and precise and may find application in other agricultural formulations containing these growth hormones.

Deep eutectic solvents as efficient solvent system for the extraction of κ-carrageenan from Kappaphycus alvarezii.

Three different deep eutectic solvents (DESs) prepared by the complexation of choline chloride with urea, ethylene glycol and glycerol along with their hydrated counterparts were used for the selective extraction of κ-carrageenan from Kappaphycus alvarezii. Upon comparison of the quality of the polysaccharide with the one obtained using water as extraction media as well as the one extracted using widely practiced conventional method, it was found that, the physicochemical as well as rheological properties of κ-carrageenan obtained using DESs as solvents was at par to the one obtained using conventional method and was superior in quality when compared to κ-carrageenan obtained using water as solvent. Considering the tedious nature of the extraction method employed in conventional extraction process, the DESs can be considered as suitable alternative solvents for the facile extraction of the polysaccharide directly from the seaweed. However, among the hydrated and non-hydrated DESs, the hydrated ones were found to be more effective in comparison to their non-hydrated counterparts.

Insights into the role of seaweed Kappaphycus alvarezii sap towards phytohormone signalling and regulating defence responsive genes in Lycopersicon esculentum

Seaweeds, an integral part of marine coastal environment, are an important food, industrial raw materials and biostimulants for crop growth due to the presence of a number of plant growth stimulants. The sap of an economically important seaweed Kappaphycus alvarezii (K-sap) is gaining momentum for sustainable intensification of agricultural productivity. In the present study, the phytohormone levels and transcript regulation of defence-related genes were studied in tomato seedlings in response to K-sap application alone and in combination with the fungus Macrophomina phaseolina, the causal agent of charcoal rot in tomato. The application of K-sap alone and in combination with fungus M. phaseolina significantly increased the concentration of ABA, IAA, SA and zeatin hormones. The enhanced transcript of pathogenesis related genes (PR-1b1, PR-3 and PR-5) was observed in response to application of K-sap alone and in combination with fungus M. phaseolina in tomato. The transcription factor, Pti4 and mitogen-activated kinase pathway gene, MPK2 also showed transcript accumulation on combined treatment of Macrophomina and K-sap. This is the first report highlighting the differential regulation of defence-related genes in accordance with phytohormone levels on application of seaweed sap.

Extraction of plant growth regulators present in Kappaphycus alvarezii sap using imidazolium based ionic liquids: detection and quantification by using HPLC-DAD technique

Three different imidazolium based ionic liquids namely 1-butyl-3-methylimidazolium hexafluorophosphate [Bmim][PF6], 1-methyl-3-octylimidazolium tetrafluoroborate [Omim][BF4] and 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide [Bmim][NTf2] were used to extract plant growth regulators (PGRs) present in the sap (K-sap) obtained by the mechanical expulsion from the fresh Kappaphycus alvarezii seaweed. [Bmim][PF6] was able to extract up to 65% of the total trans-zeatin and about 18% of the total indole-3-acetic acid (IAA) present in the sap as estimated by using a HPLC-DAD (diode array detector). However [Bmim][NTf2] was not able to extract any of the PGRs. Furthermore, addition of [Omim][BF4] to the sap resulted in the formation of an instant white precipitate with trans-zeatin preferentially bound on it. From the overall studies, it was concluded that [Bmim][PF6] can be effectively used to extract PGRs from seaweeds or plant extracts.

Production of partially reduced graphene oxide nanosheets using a seaweed sap

Large-scale and low-cost production of graphene is widely achieved by the chemical reduction of graphene oxide (GO). In this study, partially reduced GO (prGO) was prepared using a seaweed sap extracted from the red seaweed Kappaphycus alvarezii (1). The seaweed sap is a plant growth stimulant used as a foliar spray. The sap consisted of both organic and inorganic micro and macro nutrients such as plant growth regulators (PGRs), flavonols, choline, glycine betaine and salts of potassium, magnesium, iron, zinc etc. In order to understand the exact component of the sap responsible for the reduction of GO, different formulations of the sap devoid of PGRs and flavonols (2) as well as all organic matter (3) were prepared. It was observed that partial reduction of GO took place in both 1 and 3, while the reduction was not successful in 2. It was concluded that the synergistic effect of both flavonols and transition metals present in the sap was responsible for the reduction. The recovered sap obtained after the isolation of prGO had a similar chemical composition in comparison to the original sap and hence could be used as a plant foliar spray.

Cross-linked thin poly(vinyl alcohol) membrane supported on polysulfone in tea polyphenol separation

ABSTRACT Cross-linked polymeric colloids are coated over porous polysulfone support by a simple method to prepare high-flux membrane for separation of tea polyphenols. The colloidal particles were prepared by electrostatic interaction and cross-linking between poly(vinyl alcohol) and maleic acid. The membrane exhibited >90% rejection of polyethylene glycol of 6000 Da molecular weight. The membranes exhibited flux of about 15–20 LMH with 70–90% polyphenol retention depending upon the coating and support types at 500 psi and had shown stability under continuous running of the separation experiments in water or methanol at pressurized condition.

Evaluation of cellulose of Valoniopsis pachynema (Martens) Børgesen for its applications in paper making

AbstractProperties of cellulose extracted from Valoniopsis pachynema, which is a commercially unexploited green seaweed found in Indian waters was evaluated for its microcrystalline properties and paper forming abilities. The crude cellulose obtained from the seaweed was found to have a high crystallinity (95%) equivalent to commercially available microcrystalline cellulose samples (e.g., HiCel™ with 91% crystallinity). When the seaweed cellulose pulp was processed to prepare paper, it was observed that the chemical and strength properties (particularly high tear) of the paper sheet are similar to the paper sheets prepared from non-wood pulps such as soft wood and bamboo, and the qualities were inferior to the ones prepared from wood pulps. Hence, this seaweed pulp can be utilized for making paper by partially blending with other pulps. Due to the presence of good quality cellulose, this seaweed can be exploited as a new source of cellulose having practical applications. Graphical abstractProperties of cellulose extracted from the green seaweed, Valoniopsis pachynema found in Indian waters was evaluated for its microcrystalline properties and paper making ability. The cellulose pulp extracted from the seaweed was processed to prepare paper without the addition of any chemicals or fillers and was found to be suitable for writing and printing.

Probing initial polymer precursor solution used in poly(dimethylsiloxane) membrane preparation by HPLC-APCI-MS and ESI-MS

The compositional aspect of the initial precursor solution in terms of molecular mass is very important as it affects the final PDMS membrane structure. Herein, analytical techniques such as electrospray ionization mass spectrometry (ESI-MS) and high performance liquid chromatography (HPLC) combined with atmospheric pressure chemical ionization (APCI) mass spectrometry [HPLC-APCI-MS] were used for characterization of dilute solutions of two commercial precursors used in the PDMS membrane preparation. The mass spectrometry results showed the presence of linear as well as cyclic macromolecular units ranging from degree of polymerization (DP) 3 to 39 in the polymer solution which indicated the polydisperse nature of the polymer. This implied that the mass spectrometry data of the dilute precursor solution are in the 200–3000 m/z range which agrees well with solution viscosity.

The occurrence of bleaching stripe disease in Gracilaria corticata and controlling of the disease using quorum quenching approach

In the present study, the Gram-negative bacteria Vibrio and Pseudoalteromonas species associated with Gracilaria corticata found to be opportunistic pathogens that caused bleaching stripe disease on its host. Consortium of these pathogens induced maximum disease symptoms with 27.3 mm long bleaching stripe. Presence of Gram-positive bacteria Bacillus reduced the disease appearances in the co-culture of Gram-negative bacteria. Each Gram-negative bacteria had capability to produce two different types of AHLs. For the first time found that in the addition of (Z-) - 4- Bromo- 5- (bromomethylene) - 2(5H)- furanone with co-culture of pathogenic bacteria and host fronds significantly minimized the bleaching stripe symptoms. Incubating of pathogenic bacteria with 8 and 10 μm ml(-1) of furanone did not able to induce disease symptoms. The present study will help to understand the chemical interaction between Gram- positive and negative bacteria in marine environment. This article is protected by copyright. All rights reserved.